Sepp Blatter resigns as FIFA president: What you need to know

Three days after winning a fifth term as FIFA president in the aftermath of the arrest of leading FIFA officials, Sepp Blatter has announced his resignation as president of football's world governing body. Here's what you need to know about Tuesday's stunning news:

Blatter resigns

Blatter announced his resignation in a hastily arranged news conference in Zurich. Blatter said a special election would be held between December 2015 and March 2016 to appoint his successor.

"FIFA needs profound restructuring," Blatter said. "Although members have given me the new mandate, this mandate does not seem to be supported by everyone. We will hold an extraordinary conference as soon as possible. A new president will be elected."

ABC: FBI investigating Blatter

ABC investigative reporter Josh Margolin says that Blatter is being investigated by the FBI and U.S. prosecutors.

"Now that people are going to want to save themselves, there's probably a race to see who will flip on [Blatter] first," one source said, explaining how the feds typically try to get people to inform on their superiors.

"We may not be able to collapse the whole organization but maybe you don't need to," one of the sources said.

Domenico Scala is the man charged with overseeing FIFA reform. In the aftermath of Blatter's resignation, he addressed the way forward.

"I have a great amount of respect for the President and the role that he has played in championing reform within FIFA. As he has recognised, we have worked hard to put in place governance reforms. But this has not been enough. By making this announcement, he has created an opportunity for us to go further than FIFA has before -- to fundamentally change the way in which FIFA is structured.

"As part of FIFA's work, the organisation will re-examine the way in which it is structured. While it would be premature to speculate on the outcomes of this work, nothing will be off the table, including the structure and composition of the Executive Committee and the way in which members of the Executive Committee are elected. I expect this to be an important aspect of ongoing reform. As I said a year ago, the structure of the Executive Committee and its Members are at the core of the current issues that FIFA is facing. Current events only reinforce my determination to drive this reform."

Prince Ali bin Al Hussein said "I am at the disposal of all national associations who want to change, including all who were afraid to make a change."

Meanwhile, UEFA president Michel Platini offered a short response to the news: "It was a difficult decision, a brave decision, and the right decision."

What changed Blatter's mind?

The 79-year-old had been defiant and feisty in the same room on Saturday, fending off questions about FIFA's battered reputation and the chance he could be arrested.

But his mood had changed in the 24 hours before his announcement, Blatter aide Walter Gagg told The Associated Press.

"We know that the in the last 48 hours he was thinking of the future and perhaps what happened in the last hours, this gave him the conviction," said Gagg, a long-time confidante of Blatter.

Gagg added: "We had lunch with him [on Monday]. He was relaxed he was fine. I had a very good meeting with him early in the morning [on Tuesday]. Then came the different information from the U.S. with this and that.''

"The Swiss authorities are now looking at the awarding of the 2018 and 2022 World Cups, he said. "If you've read all the journalism around it, you'd certainly have doubts about the Qatar World Cup. If that is shown to be true and they can demonstrate that there was corruption then of course it should be rebid."